In the field of industrial automation, inspection systems have long been applied to inspect, detect defects in, and sort containers such as boxes. Conveyers are often used to deliver the containers to and remove them from the inspection system. For example, U.S. Pat. No. 4,165,939 issued in 1979 and discloses an inspection system for detecting dimensional tolerances, shape, and cosmetic defects in containers. A conveyer carries the containers past an inspection point where at least one focused beam of radiant energy traverses the surface of the container at a steep angle. The pattern of the surface is detected and evaluated by optical imaging techniques to determine the acceptability of the inspected container while maintaining a capability of making allowances for manufacturing tolerances of the relative position of the area under inspection with respect to a given reference point of the container. The inspection process is initiated and terminated depending upon the translational position of the container with respect to the inspection system.
U.S. Pat. No. 5,802,803 discloses a case packer comprising an inspection unit, a packing unit, and a sorting unit. The inspection unit is disposed on an upstream side of a path of transportation for packaged products for inspecting each of the products being transported on the path and thereby distinguishing defective products from normal products. The packing unit is disposed on a downstream side of the path for packing a specified container simultaneously with products delivered to the container in a plurality of rows on the path. Finally, the sorting unit is disposed between the inspection unit and the packing unit along the path for discharging the defective products away from the path and arranging the normal products in the plurality of rows on the path.
Optoelectronic sensors for detecting and locating objects are valuable in a wide variety of fields, including industrial automation. Photoelectric sensors, which comprise a type of optoelectronic sensor, have long been used to detect and locate objects. For example, U.S. Pat. No. 3,750,877 issued in 1973 and discloses an apparatus for inspecting the walls of containers. The apparatus uses a light-emitting device, a photosensitive device, and a high-speed rotatable carrier for serially moving each of the containers between such devices to enable any undesirable opening (i.e., an edge crack) in the walls of the containers to be detected by light passing through the walls to energize the photosensitive device which in turn actuates a mechanism to reject the particular defective container.
U.S. Pat. No. 5,141,111 is titled “System and Method for Inspecting and Rejecting Defective Containers.” The system includes a plurality of reflective infrared sensors, an electronic logic control, and a container-removal device. The system assesses the quality of the flange of the container and senses the height of the container by sensors irradiating the flange portion of the container with narrow beams of infrared light at varying heights and receiving radiation reflected from the flange portion. The acceptability of the container is determined by the quantum of reflected radiation received by the sensors. Unacceptable containers are removed by a high-speed pneumatic cylinder.
U.S. Pat. No. 6,757,420 is titled “Inspection Device for Packages” and discloses an automatic inspection device. The device determines whether sealed blister packages, consisting of a blister container and a cover film, are free of defects in the blister container, the sealing seam, or the perforation. At least two light sources are arranged at a certain distance from one another and each emit a light bundle at a predetermined wavelength range, whereby the emission maxima of the two light sources are offset in relation to one another. The light sources are arranged such that the packages are vertically illuminated. The light reflected by the packages is recorded by a CCD camera and the digital images are stored in a computer, so that they are available in a computer-supported image-processing and documentation system.
Many entities have worked toward improving the conventional inspection systems. For example, Cognex Corporation is a manufacturer of machine vision systems, software, and sensors used in automated manufacturing to inspect and identify parts, detect defects, verify product assembly, and guide assembly robots. Cognex is headquartered in Natick, Mass. One particular Cognex system is disclosed in U.S. Patent Publication No. 2008/0310676 titled “Method and System for Optoelectronic Detection and Location of Objects.”
Disclosed in the patent publication is a system for optoelectronic detection and location of moving objects. The system captures one-dimensional images of a field of view through which objects may be moving, and makes measurements in those images. The system selects from among those measurements those that are likely to correspond to objects in the field of view, makes decisions responsive to various characteristics of the objects, and produces signals that indicate those decisions. The disclosed system is touted as providing excellent object discrimination, electronic setting of a reference point, no latency, and high repeatability.
Machine vision systems such as those of Cognex can cost many thousands of dollars and include extremely complex components such as cameras, lenses, and digital processors. Generally, machine vision systems apply computer vision to industry and manufacturing. Whereas computer vision is mainly focused on machine-based image processing, machine vision most often also requires digital input/output devices and computer networks to control other manufacturing equipment such as robotic arms. Machine vision systems combine computer science, optics, mechanical engineering, and industrial automation.
Defective boxes can damage on-line production machines, cause of loss of product, and result in unusable, or even dangerous, boxes. Nevertheless, no simple, cost-effective, automatic system exists to detect certain types of defects in shipping boxes. Boxes may be manually inspected, of course, for defects and proper dimensions. Manual inspection has several disadvantages. For example, modern production lines, such as container manufacturing and filling operations, typically operate at very high speeds. Manual inspection of boxes moving at such speeds is difficult.
Therefore, there remains a need in the art for an improved system for inspecting boxes that overcomes the shortcomings of conventional inspection systems. To overcome the shortcomings of the current solutions applied to inspect boxes, a new box inspector is provided. An object of the present invention is to inspect boxes filled with items to determine the presence of defects in the boxes or the absence of items from the boxes. Another object is to simultaneously inspect a box for one or more of dimensional conformity, gaps between flaps, and the presence of items within the box.
Yet another object is to decrease the cost and complexity of the machinery used to inspect boxes. A related object is to provide a system that does not scan the box under inspection. A further related object is to use fixed position beams to inspect the boxes. An additional object is to identify unacceptable boxes without disrupting production speeds or interrupting conveying equipment. It is still another object of the present invention to correlate the translational speed of the box under inspection with the inspection system. A related object is to permit adjustment of the box inspector to meet the specific requirements of a particular application.